JP2001230780A - Fault detector in asynchronous transfer mode transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault detector in an asynchronous transfer mode transmitter that can detect a fault for each function block in the ATM transmitter by separating each function block from an ATM network. SOLUTION: A test cell transmission section 11 transmits a test cell in a forward path direction via a cell transmission line 14. LBF-x (x=a-c) fields whose number is equal to the number of the function blocks 10a-10c in the ATM transmitter 1 are provided in a payload of this test cell. The function blocks 10a-10C copy the test cell, separates the copied test cell from the original test cell, writes data denoting a loopback to the LBF-x fields of the separated test cell and inserts the resulting cell to a cell transmission line 15. A test cell reception section 12 detects a function block not normally sending the test cell as a fault location.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an asynchronous transfer mode (ATM).
M ”. ) Switches and mobile communication base stations (BTS: Base)
The present invention relates to a failure detection device that realizes failure detection of a cell transmission line in an ATM transmission device connected to an ATM line, such as an ATM transmission device.

[0002]

2. Description of the Related Art In an ATM network, it is necessary to monitor failures and performances in the network, and when there is an abnormality, it is necessary to detour to another route or switch a device to a spare.

In order to operate and manage this ATM network, an ITU-T (International Telecommunications Un
In ion-Telecommunication Sector, OAM (Opera
and management are specified. One of the OAM tests is a loop-back test. By using the loop-back test, the conduction state of a specific section can be monitored, and a failure of the specific section can be detected.

[0004] Loopback tests are performed using loopback cells. This loopback cell includes an OAM cell type indicating that this cell is a loopback cell,
OAM function type, loopback display indicating whether the received loopback cell is loopback, correlation tag indicating correspondence between transmitted loopback cell and received loopback cell, loopback location indicating loopback position ID, a source ID indicating a device into which the loopback cell is inserted, and a CRC (Cyclic R) used for error detection of payload information of the loopback cell.
edundancy Check) -10.

[0005] By using this loopback function, it is possible to specify which transmission line or ATM exchange in the ATM network has a failure or failure. As a failure detection device using this loopback function, there is a technology that assigns a loopback location ID of a loopback cell to each functional block divided in the device, thereby looping back the loopback cell for each functional block. It is disclosed (JP-A-11-1
No. 22261).

[0006]

However, in such a conventional ATM transmission equipment,
Since this cell is looped back by assigning a loopback location ID for each functional block, loopback is limited to one functional block in the apparatus for one test cell. For this reason, it is necessary to transmit the test cell several times in order to specify the failure location.

[0007] The loopback ID is assigned by ATM.
Since this device depends on the network system, if this device is replaced with a new transmission device, etc., and the classification within the device of the new transmission device is changed, the classification within the new transmission device is set again at the maintenance center, etc. Must.
Therefore, in order to facilitate the loopback test, it is preferable that failure detection can be performed in the ATM transmission device separately from the ATM network.

[0008]

The present invention employs the following structure to solve the above problems. <Configuration 1> A failure detection device in an ATM transmission device according to the first aspect of the present invention is connected to an asynchronous transfer mode line network to transmit cells, and has a functional block for realizing the function of the device. Provided for each function,
In an asynchronous transfer mode transmission device sequentially connected via transmission lines in the forward direction and the return direction, a test cell for failure detection in which a predetermined field corresponding to each functional block is provided in the device, in the forward direction. A test cell transmitting unit for transmitting to the functional block via the transmission path, receiving the test cell transmitted from the functional block via the transmission path in the backward direction, and receiving and writing data in a predetermined field of the test cell; A test cell receiving unit that detects a failure of each functional block based on the number of test cells that have been set, and recognizes the test cell transmitted from the test cell transmitting unit in each of the functional blocks, and A test cell separating unit for copying and separating from the original test cell, and a predetermined field corresponding to the function block of the test cell separated by the test cell separating unit A test cell writing unit for writing data indicating a return in the functional block, and a test cell insertion unit for inserting a test cell in which data is written by the test cell writing unit into a transmission path in the backward direction. did.

<Structure 2> In the failure detecting device in the ATM transmission device according to the second aspect of the present invention, the test cell transmitting section provides a predetermined field corresponding to each functional block in a payload section following a header of the test cell, It is configured to initialize and transmit the field.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. <Specific Example 1> In specific example 1, a test cell is generated, copied, and turned back in an ATM transmission device separately from an ATM network, so that a failed portion can be detected in the ATM transmission device.

FIG. 1 is a block diagram showing the configuration of the first embodiment. The ATM transmission devices 1 to 3 are devices for performing ATM routing, disassembling and assembling cells, and transmitting ATM cells. The ATM transmission device 1 includes a cell transmission path (forward direction) 14, a cell transmission path. (Return direction) 15 are connected to the adjacent ATM transmission devices 2 and 3 respectively. The ATM transmission device 2 is further connected to the maintenance center 4 via an ATM line, thereby forming an ATM network.

The ATM transmission devices 1 to 3 include functional blocks (packages) 10 a to 10 c and a test cell transmitting unit 11.
, A test cell receiving unit 12 and a control unit 13.

The function blocks 10a to 10c are blocks provided for each function in order to realize the functions of the ATM transmission device. In the specific example 1, the functional blocks 10a and 10c function as interfaces for connecting to the ATM transmission devices 2 and 3.

The test cell transmitting unit 11 is connected to the cell transmission line 14 and transmits a test cell via the cell transmission line 14 in the forward direction. The test cell is provided with a predetermined field corresponding to each functional block, which will be described later.

The test cell receiving unit 12 is connected to the cell transmission line 15 and recognizes and receives the test cell transmitted in the backward direction, the data indicating the return written in the test cell and the number of received test cells. The failure location is detected based on the The control unit 13 controls the function blocks 10a to 10c, the test cell transmitting unit 11, and the test cell receiving unit 12 via the control bus 17.

FIG. 2 is a block diagram showing the configuration of functional blocks 10a to 10c in the ATM transmission devices 1 to 3.
Each of the functional blocks 10a to 10c includes an individual processing unit 1.
00, the test cell separation unit 101, and the test cell writing unit 1
02 and a test cell insertion unit 103.

Individual processing unit 100, test cell separation unit 10
1. The test cell insertion unit 103 includes the cell transmission lines 14,
15, the test cell separation unit 101, the test cell writing unit 102, and the test cell insertion unit 103 are connected via a loopback cell transmission line 16.

The individual processing section 100 is a block for executing processing for realizing functions. Test cell separation unit 10
Reference numeral 1 denotes a block for recognizing, copying, and separating the test cells transmitted from the test cell transmitting unit 11 via the cell transmission line 14.

The test cell writing unit 102 is a block for writing data indicating a return to the test cells separated by the test cell separation unit 101. The test cell separation unit 101 and the test cell insertion unit 103 are connected by the loopback cell transmission line 16. Is connected to The test cell insertion unit 103 is a block that inserts the test cell in which the data indicating the return is written by the test cell writing unit 102 into the transmission path 15 in the backward direction.

FIG. 3 is an explanatory diagram showing the format of a test cell. In the area of the first 5 bytes of the test cell, A
The same 4-byte ATM header and 1-byte HEC (Header Error Control) are written as in the TM basic format. This ATM header includes a connection VPI (Virtual Path ldentifer) and V
Indicates CI (Virtual Channel ldentifer).

[0021] The payload portion (48 bytes) following the above
Has the same number of LBFs as the number of functional blocks (packages) 10a to 10c in the ATM transmission device 1 to be detected.
_x (x = a to c) fields are set. This LBF
Return in the function block 10x in the _x field (LoopBac
Data indicating k) is written.

In the first embodiment, as shown in FIG. 1, since there are three functional blocks 10a to 10c, LBF_a, LBF_b, and LBF_c fields having a total of 3 bytes are set. Note that the payload after the LBF_a, LBF_b, and LBF_c fields is DC (Don't care).

<Operation> Next, the operation of the first embodiment will be described.
When performing a failure detection, a failure detection request is transmitted from the adjacent ATM transmission devices 2 and 3 or the maintenance center 4 of the ATM network to the control unit 13 of the ATM transmission device 1, and the request is transmitted from the control unit 13 to the control bus 17. The data is transmitted to each of the functional blocks 10 a to 10 c, the test cell transmitting unit 11, and the test cell receiving unit 12.

FIG. 4 is an explanatory diagram showing the operation when there is no failure. The test cell transmitting unit 11 generates a test cell LBC in response to the failure detection request. Then, LBF_a, LBF_a, LBF provided in the payload section of the test cell LBC
All bits “0” are written in the BF_b and LBF_c fields.

The test cell LBC is first transmitted to the functional block 10a via the cell transmission line 14, and is input to the test cell separating unit 101 via the individual processing unit 100 of the functional block 10a.

The VP of the ATM header of the test cell LBC
Since I and VCI indicate that the connection is dedicated to a test cell, the test cell separating unit 101 recognizes that this cell is a test cell, and the test cell LBC
Is copied to generate a test cell LBC_a.

The original test cell LBC is transmitted as it is via the cell transmission line 14, and the separated test cell LBC is transmitted.
BC_a is transmitted to the test cell writing unit 102 via the loopback cell transmission line 16.

In the test cell writing section 102, the test cell L
All bits “1” are written in the LBF_a field of BC_a, and the test cell LBC_a is transmitted to the test cell insertion unit 103 via the loopback cell transmission line 16. The test cell LBC_a is inserted into the transmission path 15 by the test cell insertion unit 103, and transmitted in the return path direction via the individual processing unit 100 of the functional block 10a.

On the other hand, the test cell LBC output to the cell transmission line 14 is input to the function block 10b. This test cell LBC is recognized by the test cell separation unit 101 as a test cell, and is similarly copied. Then, the test cell LBC_b is separated from the test cell LBC.

Then, the test cell writing section 102
LB of test cell LBC_b separated from test cell LBC
All bits “1” are written in the F_b field. This test cell LBC_b is inserted into the transmission line 15 by the test cell insertion unit 103, and is transmitted in the backward direction.

Further, the test cell LBC output to the cell transmission line 14 is input to the function block 10c, and the same processing as that of the function blocks 10a and 10b is performed, thereby obtaining the LBF.
The test cell LBC_c in which all bits “1” are written in the _c field is transmitted from the functional block 10c via the cell transmission line 15 in the backward direction.

Therefore, the function blocks 10a, 10b, 1
If there is no failure in 0c, one test cell LBC_a, one LBC_b, one LBC_c is transmitted via the cell transmission line 15.

Since the ATM headers of the test cells LBC_a, LBC_b, and LBC_c transmitted via the transmission line 15 indicate the test cell dedicated connection, the test cell receiving unit 12 determines that these cells are test cells. recognize.

If all the bits “1” are written in the LBF_a field of the test cell, the test cell receiving unit 12 recognizes that the test cell is the test cell LBC_a turned back from the functional block 10a, and The cell LBC_a is received by the test cell receiving unit 12. Test cells LBC_b and LBC_c are also included in test cell receiver 1
2 is also received.

Then, the test cell receiving section 12 sends the corresponding LBF_a, LBF_a, LBF_a, LBF_c of the test cells LBC_a, LBF_b, LBF_c.
All bits “1” in the BF_b and LBF_c fields
Is written in each function block 10
It is determined that no fault has occurred in a, 10b, and 10c.

The result of detection by the test cell receiving unit 12 is transmitted to the control unit 13 via the control bus 17. In the control unit 13, the received failure detection result indicates that the maintenance center 4 or the adjacent ATM transmission device 2, which has output the failure detection request,
3 is sent.

Next, a failure detection operation when any one of the functional blocks 10a to 10c fails will be described. FIG. 5 is an explanatory diagram showing an operation (1) when the functional block 10c fails as an example.

As shown in FIG. 5, the test cell receiving section 12
Should receive three folded test cells, but receive only test cells LBC_a and LBC_b and test cell LBC
When _c is not received, it is considered that the test cell LBC transmitted from the function block 10b to the function block 10c is discarded inside the function block 10c, and therefore,
The function block 10c is detected as a failure location.

It should be noted that the test cell receiving section 12 sets the test cell LBC
_a, LBC_b, and LBC_c, all of the received test cells LBC_a, LBC_b, and LBC_c
If the data written in the F_a, LBF_b, and LBF_c fields is abnormal, the corresponding function block 10a
Of the test cell writing unit 102 is detected as a failure point.

FIG. 6 is an explanatory diagram showing the operation (2) when the functional block 10b fails. As shown in FIG. 6, the test cell receiving unit 12 transmits the test cells LBC_a, LBC
When the test cell LBC_b is received and the test cell LBC_b is not received, the test cell LBC includes the individual processing unit 100, the test cell separation unit 101, and the test cell writing unit 10 of the functional block 10b.
2. It is considered that the test block is discarded in any of the test cell insertion units 103, and therefore, the functional block 10b is detected as a failure point.

FIG. 7 is an explanatory diagram showing the operation (3) when a failure occurs in the functional block 10b. As shown in FIG. 7, when the test cell receiving unit 12 should receive three folded test cells, the test cells LBC_a, LBC_b,
When LBC_b and LBC_c are received, it is considered that one of the test cell separation unit 101, the test cell insertion unit 103, the loopback cell transmission line 16, and the individual processing unit 100 has failed.

That is, the test cell separating unit 101 sets the test cell L
When the BC is copied twice, when the test cell separation unit 101 inserts the test cell LBC into the cell transmission line 15 twice, when the individual processing unit 100 copies the test cell LBC twice, the two The test cell LBC_b is transmitted. Therefore, when the test cells LBC_b overlap, any of the above blocks is detected as a failure location.

FIG. 8 is an explanatory diagram showing the operation (4) when a failure occurs in the functional block 10b. As shown in FIG. 8, when the test cell receiving unit 12 should receive three folded test cells, the test cells LBC_a, LBC_b,
When five of LBC_b, LBC_c, and LBC_c are received,
It is considered that one of the individual processing unit 100 and the test cell separation unit 101 of the functional block 10b has failed.

That is, the individual processing unit 100 sets the test cell LBC
Is copied twice, and when the test cell separation unit 101 copies the test cell LBC twice, two test cells LBC_b are transmitted from the functional block 10b.

In this case, from the function block 10c, 2
Since two test cells LBC_c are transmitted to one test cell LBC, the failure of the function block 10b on the test cell LBC transmission side is determined before determining the failure of the function block 10c. Therefore, the test cells LBC_b and LBC
When _c overlaps, any of the above blocks of the functional block 10b is detected as a failure point.

<Effects of Specific Example 1> As described above, according to Specific Example 1, one test cell LBC is transmitted from the test cell transmitting unit 11 in the ATM transmission apparatus, and this test cell LBC is Copy in the function blocks 10a to 10c,
Because it was separated, written and turned back, AT
Failure detection can be performed in the ATM transmission device separately from the M network, and failure detection in the ATM transmission device can be performed for each functional block.

In addition, since the failure can be detected by transmitting the test cell once, it is possible to detect the failure location in each ATM transmission device in a short time, and to perform the failure detection separately from the ATM network. Even when a new ATM transmission device is replaced and the section in the transmission apparatus is changed, it is not necessary to set the section in the apparatus again in a network system such as a maintenance center, and the failure point can be easily detected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a specific example 1.

FIG. 2 is a block diagram illustrating a configuration of a functional block of a specific example 1.

FIG. 3 is an explanatory diagram of a format of a test cell of a specific example 1.

FIG. 4 is an explanatory diagram showing an operation of the specific example 1 when there is no failure.

FIG. 5 is an explanatory diagram illustrating an operation (1) when a functional block fails according to the first embodiment;

FIG. 6 is an explanatory diagram showing an operation (2) when a functional block fails according to the first embodiment;

FIG. 7 is an explanatory diagram showing an operation (3) when a functional block fails according to the first embodiment;

FIG. 8 is an explanatory diagram showing an operation (4) of the specific example 1 when a functional block fails.

[Explanation of symbols]

 1-3 ATM transmission apparatus 10a, 10b, 10c Functional block 11 Test cell transmitting unit 12 Test cell receiving unit 13 Control unit 101 Test cell separating unit 102 Test cell writing unit 103 Test cell inserting unit

Claims (2)

[Claims] 1. A device for transmitting cells by being connected to an asynchronous transfer mode line network, wherein a function block for realizing the function of the apparatus is provided for each function, and a transmission path in a forward direction and a return direction is provided. Asynchronous transfer mode transmission devices that are sequentially connected via a transmission line, transmit a test cell for failure detection, in which a predetermined field corresponding to each function block is provided, to the function block via the transmission line in the outward direction. A test cell transmitting unit that receives a test cell transmitted from the functional block via the transmission path in the backward direction, and based on the written data in a predetermined field of the test cell and the number of received test cells, A test cell receiving unit that detects a failure of a functional block, wherein each of the functional blocks recognizes a test cell transmitted from the test cell transmitting unit,
A test cell separation unit that copies the test cell and separates it from the original test cell, and a predetermined field corresponding to the function block of the test cell separated by the test cell separation unit indicates the return of the function block. An asynchronous transfer mode transmission device, comprising: a test cell writing unit that writes data; and a test cell insertion unit that inserts a test cell into which data is written by the test cell writing unit into a transmission path in a return path. Failure detection device. 2. The test cell transmitting section according to claim 1, wherein a predetermined field corresponding to each functional block is provided in a payload section following a header of the test cell, and the field is initialized and transmitted. Failure detection device in the asynchronous transfer mode transmission device of the above.